Foldable alpha-frame for excavating machines



E. w. TAYLOR ET AL FOLDABLE A-FRAME FOR EXQAVATING MACHINES 7 Nov. 19, 1946.

Filed Aug 25, 1944 2 Sheets-Sheet l z n Z. a M W #7 \Q gm 6 32 NOV. 19, 1946. w, TAYLQR ET AL 2,411,305

FOLDABLE A-FRAME FOR EXCAVATING MACHINES Filed Aug. 25, 1944 2 Sheets-Sheet 2 Pei e2 406 68/7.

Patented Nov. 19, 1946 FOLDABLE A-FRAME. FOR EXCAVATING MACHINES Ernest W. Taylor and Peter Nielsen, Bay City,

Mich, assignors to Industrial Brownhoist Corporation, Bay City, Mich.

Application August 25, 1944., Serial No. 551,174

3 Claims.

, This invention relates to foldable A-frames for excavating machines or other machines equipped with booms.

,Excavating machines; and particularly cranes of the shovel, clamshell, and dragline type are readily mobile, so that they can be moved from one job to another; and there is used as a part of the. structure, a so-oalled A-frame, certain portions of which project above the machine structure over which certain of the operating cables of the machine are trailed and by means of which the elevation of the boom and operation of other parts of the machine is accomplished.

In the transportation of machines of this character from one location to another, it is necessary that they pass under overhead structures such as highway bridges, grade crossings, wires, and

the like; and in certain instances the overhead clearances on the job itself are limited. It is therefore desirable that the A-frame structure be designed so as to be as low as possible in order that the machine may pass underneath low bridges, over-passes, or other obstructions. However, an A frame that is low enough for such overhead clearances runs up the compressive loading of the boom very materially, increasing its weight and decreasing the live load handling capacity of the crane. An appreciably higher A- frame reduces the loading on the boom, allowing a reduction in the weight, thus increasing the available lifting capacity of the crane for live loads. Therefore, it is a prime object of the invention to provide an A-frame construction which can be adjusted to a 'low height when overhead conditions require that, and to a higher clearance for handling maximum loads when overhead conditions permit.

. Another object is to provide a foldable A- frame, the upper section of which is readily foldable upon the roof of the crane cab structure, and which can be quickly and easily raised, by power, and without strain or snapping of the various cables, etc., whenthe machine is spotted and ready for operation.

A further object is to design an A-frame of simple, practical, and substantial construction, which can be easily manufactured and assembled, and which can be easily raised or folded, and in a minimum length of time.

In order to provide a more precise understanding of the nature and objects of the invention, one specific embodiment will be described in connection with the accompanying drawings in which:

Fig. 1 is a side elevational View of an excavating machine, the solid lines showing the A- frame raised, the broken lines showing the upper section in folded position;

Fig. 2 is an enlarged side, elevational View of the A-frarne, the broken lines illustrating the upper section in folded position;

Fig. 3 is a rear, elevational view;

Fig. 4 is a fragmentary, side, elevational view illustrating the cable protecting means;

Fig. 5 is also an enlarged, fragmentary, side, elevational view showing the upper end of the foldable section;

Fig. 6 is a top plan view thereof; and

Fig. 7 is a fragmentary, side, elevational view illustrating the detachable securing means.

Referring now to the drawings, the numeral it indicates the base of a crane which is carried by suitable crawlers or traction devices I l, the base having mounted thereon a suitable platform ii on which the mechanical equipment of the excavation mechanism (not shown) is mounted, this machinery being housed in a, cab structure l3 as usual.

A boom 14 is pivotally mounted for swinging movement about the pivot point l5, and sheaves l6 are journaled on a pin I! provided on the outer end of the boom. A hoist drum I8 is mounted on the platform 12 of the crane, and a hoist rope l9 is wound thereon, thence leading over the sheave l5, and thence to a, fall block 2 5 as usual so that any desired hoisting operation can be accomplished.

An A-frame Wis mounted on the platform 12 and is made up of compression struts or bars 22,

t the lower ends of said struts being connected to the crane platform at 23, the upper ends being formed with suitable openings (not shown) to accommodate a horizontally disposed shaft 24, 1

and while the A-frame comprises two sides which are identically similar, we shall, for the purpose of this description, describe but one side only. Stays 25 are connected to the platform 12 at the point 2 6 with the upper ends connected to the shaft 24, and a cable protecting member 21 is mounted on said shaft, the face of said member being crowned as shown and for a purpose to be hereinafter described.

Compression bars 28 form a part of the upper foldable portion of the A-frame and are connected to the shaft 24, the upper end being bifurcated as at 29 and a horizontally disposed shaft 30 is mounted on the upper end as usual.

Tension members 3| are connected to the platform I2 at the point 32, the upper ends being connected by a shaft 33 to which the lower ends of the links 34, which form a part of the upper foldable part of the A-frame, are also connected, the upper ends of the links 34 being connected to the horizontally disposed shaft 35, and links 36 are also connected to the shaft 35 at a point intermediate their length, the lower ends being bifurcated as at 3], and openings 38 are provided in the lower end of the links 36 in register with a imilar opening 39 provided in the links 34, bolts 40 serving to rigidly secure the said links 34 and 36 together as a-rigid structure when the A-frame is in raised position.

The shaft 30 together with the links 28, 34 and 36 complete the foldable upper section of the A-frame.

Attached to the shaft 36 are the links 40a, to which the back stay 4| is connected, sheaves 42 being journaled on said links and form a part of the assembly. The back stay 4| is connected to a sheave cage 43 in which the sheaves 44 are mounted, similar sheaves 45 being mounted in the sheave cage 46 and the boom hoist line 41 is trained over the various sheaves 44 and 45, thence being wound on the hoist drum 48 as usual. A boom line 43 is connected to the cage 46 with the opposite end anchored to the outer end of the boom, and it will be obvious that rotation of the winding drum 48 will raise or lower the boom accordingly.

When it is desired to collapse the A-frame for travel from one location to another, the end of the boom is first lowered to the ground or onto a support (not shown), to slack the boom hoist line 41, the bolts 40 re then removed, permitting the links 34 and 36 to jackknifeon the shaft 35 and the links 28, 34, and 36 to swing on the shafts 24,30 and 33, so that the parts assume position as clearly indicated in broken lines of Figs. 1 and 2 of the drawings, the back stay cable 4| restin on the crowned face of the memberZ'l, and the top of the A-frame will then be substantially flush with the top of the cab structure l3 and will readily clear all highway bridges, overpasses, and similar obstacles, a block and tackle assem- 'bly being connected to the shaft 35 and to lugs 5| provided on the rear end of the cab, and a handle 52 being provided for tightening or loosening as desired, this block and tackle arrangement being of conventional design at present on the market. 7

When the A-frame is folded as indicated in broken lines in Figs. 1 and 2, and it is desired to raise it preparatory to hoisting operations, the operator actuates the boom hoist drum '48 in the usual manner, thus winding in the cable 41, and placing strain on the hoisting cable which first swings the link members 28, 34 and 36 upwardly,

automatically swinging them to position indicated in solid lines, the bolts 4|] are then inserted; the block and tackle assembly 5|) is removed, and the machine is now ready for work, the raising, is 'quick, easy nd. smooth, there is no jerking or undue strains, and no rearrangement of heavy assembly is required by the operator.

-The herein described construction and arrangement admits of considerable modification without departing from the invention; we therefore do not wish to be limited to the prev cise arrangement shown and described, which is with said hoist means and comprising a station- 7 ary, low arch section and an upper high arch section, tension members on the body, links pivotally connecting said upper section and the tension members respectively, the links being pivotally connected at their inner end portions, with one end of one link overlapping the other, quickly removable means for securing the free overlapping end of the one link to the companion link to provide a rigid structure, said means permitting folding of the high arch section when removed, and manually operable means connected to said links and to the crane body to prevent a snapping action when the high arch section is raised.

2. A machine as defined in claim 1 in which a crown-shaped cable protecting member spans the upper end of the low arch section of the A- frame.

' 3. In a crane of the class described, in combination, a crane body, a'boom movably mounted thereon, an A-frame mounted on the body and comprising upper and lower sections, tension members on the body, the upper A-frame section being pivotally mounted on the lower section, hoisting instrumentalities on the crane for raising and/or lowering the boom, and including a back stay, means permitting the upper section of the A-frame to swing to folded position, said means including pivotally connected foldable links connecting the upper section and the tension members respectively, one end of one link being bifurcated to accommodate the end section of the companion link, quickly removable means spaced a predetermined distance from the pivotal connection of the linksfor locking them against pivotal movement and form a rigid structure, a crowned member on the lower section of the A-frame and over which the back stay leads when the upper section 'is in folded position, and an adjustable block and tackle means connected to the links of the upper section of the A-frame and to the crane body to prevent snapping of the A-frarne memberswhen said frame is swung to raised position.

ERNEST w. TAYLOR, PETER NIELSEN. 

